1. Technical Field
This invention relates to the field of cable data delivery systems and, more particularly, to the collection of usage statistics data for billing subscribers in a more flexible manner and for provisioning equipment for providing services at a desired quality of service.
2. Description of the Relevant Art
Cable television transmission systems have been utilized since the 1980's for the transmission of data, point-to-point or point-to-multipoint at T1 carrier rates of 1.544 megabits per second in a cable television system environment. Scientific-Atlanta, Inc. introduced and marketed a product known as the Model 6404 Broadband Data Modem in the early 1980's. One user coupled to a cable television distribution network can communicate to the world or two users, coupled to the cable television distribution network having a 0-54 Megahertz upstream or reverse path and a typical downstream path at frequencies above this range, can communicate with each other or with the world via a telephone central office. The upstream and downstream channels are spaced at approximately 750 kHz spacing; the modulation scheme is quadrature amplitude modulation, for example, 16-QAM. Each of two parties coupled to the cable television network can communicate in real time in a full duplex manner with each other, each having an upstream and a downstream radio frequency path. A Model 6440 frequency translator translates the upstream channel path frequency to the downstream channel path frequency for each party as necessary. Up to 24 voice or data telecommunications channels are provided by such equipment. As is known in the data communication arts, such channels can be grouped to provide digital data services at variable data rates, for example, 64 kbits/sec, 256 kbits/sec or even 1.544 mbits/ sec.
The radio frequency 0-54 MHz return path of a cable television system has been avoided by cable television system operators because it is notoriously noisy and the expense of adding reverse path amplifiers for return communications was not considered worth the investment by many in the industry until the late 1980's with the advent of impulse pay per view services. Instead, a telephone data return path has been used since the 1970's for return of data from a cable subscriber for service selection, home shopping, energy management and other purposes. U.S. Pat. Nos. 5,142,690; 5,155,590; 5,235,619 and 5,251,324 describe a cable television radio frequency reverse path data return system used for impulse pay per view services among other applications including collection of viewing usage statistics. U.S. Pat. No. 4,912,721 describes an upstream data path whereby the data is spread across an upstream television channel for transmission so as to avoid upstream noise ingress.
Digital data delivery services including digital audio and other services were also pioneered by Scientific-Atlanta. U.S. Pat. No. 5,239,540 describes a digital data delivery service for, for example, digital audio, game or software delivery to the home using quadrature partial response modulation (QPR). In allowed U.S. patent application Ser. No. 08/352,162, filed Dec. 1, 1994, and entitled "Secure Authorization and Control Method and Apparatus for a Game Delivery System," there are described a number of different ways of billing for digital data services, in particular, game services, for example, in an "arcade" mode where a user plays as many programs as the user wishes within an allocated time period, for example, a number of hours for a set fee or in a pay-per-play mode where the game can last for a long time but the fee charged for play remains the pay-per-play fee. A periodic service offering method and apparatus is described by U.S. Pat. No. 5,604,528.
U.S. Pat. Nos. 5,347,304 and 5,586,121 describe an asymmetric network in which one path to a computer or work station is via a cable network such as a cable television network and the other path is via the telecommunications network. The '121 patent describes a network manager which handles or controls the forward (downstream) and return (upstream) communication to establish interactive full-duplex real-time network sessions between a host and a selected client device. Connection to the network is managed based on parameters such as the amount of times a device's channel requests have gone unfulfilled. The upstream channels are assessed as to quality based upon error rates, noise floor and signal-to-noise ratio. Channel quality monitoring for errors and signal-to-noise ratio is done transparently to the user and the applications. A failure in periodic upstream "heartbeat" messages at selected time intervals can indicate an upstream channel failure and necessitate a channel reassignment.
Recently, Scientific-Atlanta has applied for United States patents in the field of data network access devices, for example, cable modems. These include U.S. patent application Ser. No. 08/627,062, filed Apr. 3, 1996, 08/738,668, filed Oct. 16, 1996 and continuation-in-part application Ser. No. 08/818,037, entitled "System and Method for Providing Statistics for Flexible Billing in a Cable Environment" of Koperda et al., filed Mar. 14, 1997. The '062 and (58170) applications describe the problem of providing multiple tiers or levels of service in a new combined telecommunications/cable television environment. These patent applications describe radio frequency forward and reverse path applications which support, not only LAN-style services, but continuous bit rate, variable bit rate and available bit rates services. It is suggested in these applications to bill subscribers who use a shared upstream/downstream radio frequency bandwidth in accordance with tiers of predetermined, peak or maximum bandwidth or bit rate. A subscriber demanding more will be denied service while a subscriber demanding the maximum bit rate or less will receive data grants to transmit at predetermined bit rates for a predetermined time interval so as to share the bandwidth with other contending subscribers.
Managing a data network which includes a large number of cable modems is often a difficult task when utilizing currently known techniques for cable modem management. Traditional network management utilizes maps or "views" for the operator to view network elements such as a cable modem. For example, a network consisting of 50,000 cable modems is typically represented by a map with 50,000 modems displayed on it. Such a map would, most likely, be useless for the operator. The map does not indicate any relationships which might exist between modems and the network, as well as other data which might be prudent for the operator to understand.
Traditional IP based network management utilizes discovery and the existence of various ARP ("address resolution protocol") caches and data contained therein to build a topology of the network. Such a mechanism is not available in the world of RF transmission. For these "limited" networks the only solution has been to include all terminal equipment, such as cable modems, grouped together on one or more maps. These maps do no indicate anything more than the fact that a symbol on the map represents a cable modem.
According, despite the several improvements in the art of providing cable data delivery services in recent years, there remains an opportunity to further provide improved method and apparatus for collecting, storing and utilizing statistics for various purposes including flexible billing arrangements, provisioning of new equipment and facilities, ensuring that a desired level of service is being met for subscribers of a cable data delivery system and for providing a more efficient and useful mechanism for indicating to the network operator the logical binding between the physical location of a cable modem, a user and the route in which the cable modem's data paths follows.